A power supply unit for an integrated circuit (IC) typically includes a battery and a voltage regulator. Voltage regulators may be used to condition the supplied voltage and to indicate status of the power supply unit. Voltage and status may change as the power drawn by a load (e.g., the IC) changes. Known voltage regulators provide status by measuring voltage and current produced by the power supply unit, but are unable to provide a direct measurement of power. Power would have to be calculated by use of a high-speed analog multiplier, which is costly at least in terms of processing resources. Known voltage regulators, which estimate average power by multiplying an average current measurement by an average voltage measurement, produce large error in the calculated average power. Also, the power drawn by the IC may change extremely rapidly, on the order of the clock speed of the IC, and slow sampling speeds of the known voltage regulators are unable to capture the effects of these rapid changes. The combined effect of these sources of error is uncertainty in the amount of power that a power supply has supplied. Therefore, a need exists to provide more accurate monitoring of energy drawn from a power supply.